Use cmake for libevent dependency

meson.build

 project('coeurl', 'cpp',
   version : '0.1',
   default_options : ['warning_level=3',
-                     'cpp_std=c++17'])
+    'cpp_std=c++17'])
 
-deps = [
-  dependency('threads', required: true),
-  dependency('libevent_core', required: true),
-  dependency('libcurl', required: true),
-  dependency('spdlog', required: true)
-  ]
+  deps = [
+    dependency('threads', required: true),
+    dependency('libcurl', required: true),
+    dependency('spdlog', required: true)
+    ]
 
+
+  libevent_dep = dependency('libevent_core', required: get_option('wrap_mode') == 'nofallback',)
 if target_machine.system() == 'windows'
-  deps += dependency('libevent_windows', required: true)
+  libevent_threads_dep = dependency('libevent_windows', required: get_option('wrap_mode') == 'nofallback',)
 else
-  deps += dependency('libevent_pthreads', required: true)
+  libevent_threads_dep = dependency('libevent_pthreads', required: get_option('wrap_mode') == 'nofallback',)
 endif
 
+if (not libevent_dep.found()
+  or not libevent_threads_dep.found()
+  or get_option('wrap_mode') == 'forcefallback'
+  or 'libevent' in get_option('force_fallback_for'))
+cmake = import('cmake')
+libevent_options = cmake.subproject_options()
+    libevent_options.add_cmake_defines({
+      'CMAKE_C_FLAGS': '-fPIC',
+      'EVENT_LIBRARY_TYPE': 'STATIC',
+      'BUILD_SHARED_LIBS': false,
+      'BUILD_SHARED_AND_STATIC_LIBS': false,
+      'EVENT__DISABLE_OPENSSL': true,
+      'EVENT__DISABLE_BENCHMARK': true,
+      })
+    libevent_options.set_override_option('werror', 'false')
+    libevent_options.set_override_option('warning_level', '0')
+    libevent_proj = cmake.subproject('libevent', options: libevent_options)
+    libevent_dep = libevent_proj.dependency('event_core_static')
+
+    if target_machine.system() == 'windows'
+      # the cmake project links the thread support into the library directly...
+      libevent_threads_dep = dependency('', required : false)
+    else
+      libevent_threads_dep = libevent_proj.dependency('event_pthreads_static')
+    endif
+endif
+
+deps += [libevent_dep, libevent_threads_dep]
+
 include = include_directories('include')
 
 lib = library('coeurl', ['lib/client.cpp', 'lib/request.cpp'],
@@ -37,11 +67,11 @@ endif
 
 pkg = import('pkgconfig')
 pkg.generate(lib,
-             libraries : [lib],
-             version : meson.project_version(),
-             filebase : meson.project_name(),
-             description : 'Simple library to do http requests asynchronously via CURL in C++.',
-             url : 'https://nheko.im/nheko-reborn/cocurl')
+  libraries : [lib],
+  version : meson.project_version(),
+  filebase : meson.project_name(),
+  description : 'Simple library to do http requests asynchronously via CURL in C++.',
+  url : 'https://nheko.im/nheko-reborn/cocurl')
 
 # No idea how to export working cmake config files, so don't do that for now
 #cmake = import('cmake')

subprojects/libevent.wrap

@@ -5,10 +5,3 @@ source_url = https://github.com/libevent/libevent/releases/download/release-2.1.
 source_filename = libevent-2.1.12-stable.tar.gz
 source_hash = 92e6de1be9ec176428fd2367677e61ceffc2ee1cb119035037a27d346b0403bb
 
-patch_directory = libevent-meson
-
-[provide]
-libevent_core = libevent_core_dep
-libevent_pthreads = libevent_pthreads_dep
-libevent_windows = libevent_windows_dep
-

subprojects/packagefiles/libevent-meson/meson.build

-project('Libevent meson wrapper', 'c',
-  meson_version : '>=0.57.0',
-)
-
-mod = import('unstable_external_project')
-
-p = mod.add_project('configure',
-  configure_options : [
-                       '--disable-openssl',
-                      ],
-)
-
-libevent_core_dep = p.dependency('event_core')
-if target_machine.system() == 'windows'
-  libevent_windows_dep = p.dependency('event_pthreads')
-else
-  libevent_pthreads_dep = p.dependency('event_pthreads')
-endif
-